Electroplating is a process widely used in industry to provide a metal coating having a desirable physical quality on a part. For example, electroplated coatings can provide abrasion and wear resistance, corrosion protection and aesthetic qualities to the surfaces of parts. Electroplated coating may also be used to build up thickness on undersized parts.
Aluminum substrates, in particular, can be difficult to plate since aluminum surfaces rapidly acquire an oxide layer when exposed to air or water, and thus tend to inhibit good adhesion of an electrodeposited film. In addition, since aluminum is one of the more anodic metals, there is a tendency to form unsatisfactory immersion deposits during exposure to a plating solution, which can cause discontinuous plating or breakdown of the plating process. Furthermore, if plating an aluminum film, plating methods usually involve the plating of pure aluminum metal onto the substrate. Although pure aluminum has an ordered microstructure and good cosmetic properties, it is relatively soft and easily scratched. Therefore, there are significant challenges to plating aluminum in industrial applications where durability is a desirable characteristic of a plated film.